A straw cup includes a container and a lid releasably attached to the container for closing a container open top. A lid body has a dispensing port and a vent each extending therethrough. The body further has a downward depending inner collar which surrounds the dispensing port. A straw extends through the dispensing port and has a mounting member provided at a lower end thereof. The mounting member is received in the inner collar and includes a flexible seal member having a downward frusto-conical shape. The seal member normally contacts an inner surface of the inner collar. The seal member is movable radially downwardly and away from the inner surface allowing an inward flow of air through the vent and over the seal member upon the introduction of a pressure differential across the vent where the pressure outside of the container is greater than the pressure inside of the container.
